Many monoclonal antibodies of mouse origin are valuable diagnostic agents. Their production by classical hybridoma techniques is frequently limited by the instability of cell lines, low antibody yields and the limitations of immunizing mice with toxic antigens. A promising alternative to the hybridoma technology is the production of recombinant antibodies. Pioneering work of the last decade showed that it is possible to amplify rearranged immunoglobulin genes from B-lymphocytes, to insert them into different vectors, and to express them in bacteria, yeast, insect, mammalian or plant cells. Moreover, the randomized combination of cloned heavy and light chain immunoglobulin gene fragments allowed the construction of mouse antibody libraries. These libraries enable the isolation of specific antibodies against particular antigens by phage display techniques. One prerequisite for generating highly diversified mouse antibody libraries, however, is the development of PCR primers capable of amplifying all rearranged immunoglobulin genes. In immunoglobulin repertoire library cloning, the homology between a particular primer sequence and its target template, as well as the diversity of a primer pool are the two most important parameters which determine the cloning efficiency and the size of a resulting repertoire library. This screening strategy allows the amplification of rearranged mouse immunoglobulin genes of individual B cell clones as well as of larger B cell populations for the construction of mouse scFv-antibody libraries.